A number of accessories have been developed to allow carrying loads while riding on a bicycle, and various types of bicycle racks are very common. Bicycle racks generally include a platform over which various types of bags or containers will be attached. Several methods have been used to attach the rack to the bike.
One popular bike rack configuration that has high load capacity has side legs supporting the platform. The lower sections of the legs are bolted to threaded eyelets in the bike frame in the area of the wheel axle. The weight carried by the platform is borne by these legs. In addition, the platform may have top stays that connect to a higher section of the bicycle to prevent the platform from moving forward or rearward.
Another type of bike rack has a cantilever configuration and is often referred to as a “seat post” rack or a “beam” rack. These types do not have legs connected to the bike frame. They have a single point of attachment to the seat post, and the seat post bears all the cantilevered weight. The attachment is made by way of a somewhat heavy bracket that clamps around the seat post. Seat post racks have advantage in that they can be installed and removed quickly. Some models do not require the use of any tools to install or remove. Also, seat post racks can be installed on bikes in which the bike frame is not equipped with the threaded eyelets to which rack legs would otherwise be attached. Seat post racks can also be installed on bikes that have disc brakes or suspension equipped bikes where the rack legs or its connections may interfere with other components of the bike.
However seat post racks have limited carrying capacity because the cantilever configuration induces a torque that generates high localized stress on the seat post and that tends to bend the seat post. Therefore, the carrying capacity of seat post racks has been lower then that of regular legged bike racks. Platforms of seat post racks have also tended to rotate about the seat post axis. This rotation could only be countered by providing greater friction of the seat post rack bracket against the seat post. The seat post rack bracket needed to be very tight against the seat post to generate sufficient friction to prevent the platform from so rotating. Fairly heavy brackets were therefore needed and the large clamping force of the bracket to the seat post damaged the seat post finish and tended to crush the seat post material. Thus, seat post racks were not suitable for thin aluminum tubing seat posts or the newer carbon fiber seat posts.
A carrier rack described in U.S. Pat. No. 5,395,017 to Naughton describes a rack for easy attachment and removal from a standard bicycle seat that includes a seat post abutment fork and a rail hanger. The seat post abutment fork is configured to at least partially encircle and abut the seat post. The rail hanger has arms that extend over the saddle rails of a standard bicycle seat at a pivot position near the knees of the rails so as to support the weight of the rack and its burden in a hanging fashion. While the pivoting rail hanger allows quick connection and disconnection to the seat rails it does not provide a sufficiently secure connection. Therefore further improvement in bicycle racks was needed and these improvements are provided by the present patent application.